Field of the Invention
The present invention relates to a wafer processing method.
Description of the Related Art
In general, the fabrication of devices such as integrated circuits (ICs) and large scale integrations (LSIs) includes the steps of setting a plurality of crossing streets (division lines) on the front side of a wafer to thereby partition the front side of the wafer into a plurality of chip regions and then individually forming the devices in these chip regions. The devices formed on the front side of the wafer are divided from each other by laser processing such that a laser beam is applied to the wafer along the streets to thereby form a laser processed groove along each groove on the front side of the wafer.
In this kind of laser processing, fine dust particles called debris are generated and scattered from the wafer in applying the laser beam. This debris is deposited on the front side of each device to cause a reduction in quality of each device. To cope with this problem, there has been proposed a processing method including the steps of forming a protective film on the front side of a wafer, next performing laser processing to the wafer with the protective film, and next cleaning the wafer to thereby remove the protective film and the debris deposited thereon (see Japanese Patent Laid-Open No. 2010-012508, for example).